Artificial Force Induced Reaction(AFIR) Method : Reaction proceses from A and B into AB can be searched very rapidly!

In the most recent version of GRRM program (GRRM14) a new technique (Aritificial Force Induced Reaction method: AFIR)
to search reaction proceses from A and B into AB has been introduced.
This method is especially effective to intermolecular reaction processes, which have been very diffcult to be searched by the ADD-following method.
As shown in the left figure above, artificial binding forces are applied between A and B.
Additional of an energy term proportional to the distance between A and B rAB
brings the potential into the lower curve shown in the right figure above, and then the
no barrier curve enforces A and B into AB smoothly. This is equivalent to application of
artificial attractive forces to bind A and B very rapidly.
Such an artificial process is not a real process, but removal of the artificial forces easily lead to
the real process. The reaction pathway with a barrier (TS) on the real potential surface can easily be obtained.
This method enables us to search binding reactions between molecules very rapidly, which have been difficult to
find out by the ADD-following method.
Although only two reactants A and B are involved in the above figure, the AFIR method can be used for many reactants, three or the more.

A reaction yielding HCH2CH2CHO from ethylene, CO, and H2 shown in the right figure below is an
important catalytc reaction called hydroformilation.
The AFIR method enables us to obtain the reaction processes without any knowledge by quantum chemical calculations
within a week, if we can use a computer.
Each reaction steps involving ethylene, CO, H2, or some others shown in the left figure below can be studied systematically
by the AFIR method. Then a combinaiton of various steps leads to the catalytc cycle without knowledge beforehand.